Wieeless receiving system



'May 15, 1923. 1,455,767

J. SLEPIAN WIRELESS RECEIVING SYSTEM Filed Dec. 31, 1921 WITNESSES: INVENTOR Patented May 15, 1923.

UNITED s'rarss PATENT OFFECE.

JOSEPH SLEIIAN, OF SWISSVALE, PENNSYLVANIA, ASSIGNOB, TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

WIRELESS RECEIVING SYSTEM.

Application filed December 31, 1921. Serial No. 528,132.

To all whom it may concern:

Be it known that I, Josnrrr SLEPIAN, a citizen of the United States, and a resident of Swissvale, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Wireless Receiving Systems, of which the following is a specification.

My invention relates to amplifying devices and particularly to wireless receiving systems.

The principal object of my invention is to provide an improved wireless receiving system, wherein received signal impulses are enormously amplified.

Anotherobject of my invention is to provide a wireless receiving system wherein undamped, continuous-wave signal impulses may be readily received without the customary heterodyning step heretofore employed.

Other objects of my invention will be apparent from the following description of the nature, mode of operation and advantages of my invention.

According to my invention, I impress the signal impulses to be detected upon a regenerative feed-back system adjusted to what, heretofore, has been considered an undesirable state, that is to say, one in which 30 an increase in the amplitude of the oscillations causes a more than proportional increase in the feed-back power, tending to maintain the oscillations continuously.

The unbalanced condition of the system, which is effective following the application of the signal impulses, is made stable a predetermined time interval thereafter by means of thermally responsive elements having a time lag in their response. The maXimum amplitude attained by the oscillations at the end of said time lag is dependent upon the intensity of the impulses tending to unbalance the system, all as will be explaine fl hereinafter.

lVith these and other objects and applications in view, my invention further consists in the details of construction and circuit arrangements hereinafter described and claimed and illustrated in the accompanying drawing wherein:

The single figure is a diagrammatic view of a wireless receiving system embodying my invention.

In the drawing, a regenerative feed-back system having an extremely large negative damping; effect is shown as comprising a three-electrode tube 1 of well known design and input and output circuits therefor. The three-electrode tube 1 comprises an anode 2, a controlling grid member 3 and a hot cathode 4, the latter being cnvrgized from a source of direct-current energy 5 through a resistor 6.

The input or grid-filament circuit includes a coupling coil 7 of a feedback transformer 8 and a coupling coil 9. The coupling coil 9 is inductively associated with a coupling coil 11 which is serially included in an antenna circuit that includes, in addition, an antenna 12, a tuning inductance coil 13 and a ground conductor An output or plate-filament circuit includes a translating device shown, as a telephone receiver 15, a direct-current source of energy 16, a tuned circuit 17 and a then nially-responsive element connected in shunt relation to the latter. The tuned cir cuit 17 comprises a series-connected, thermally-responsive resistor element 19 and a condenser 21 and a coupling coil 22 of the feed-back transformer 53 connected in shunt relation thereto. The feed-back coupling between the coupling coils 7 and 22 is so adjusted as to provide a regenerative system having an extremely large negative damping effect.

The thermally-responsive resistor element 18 is preferably one having an extremely large negativex-temperature coe'llicient and a definite time lag in its response to chain in the amplitude of the alternating potential drop across the tuned circuit 17, said time lag being of the order of the short st essential period in the signal to be received, that is, about .015 of a second for telephony signals and a few l'iundredths of a second for telegraphy signals.

Que such device having the above characteristics may be constructed of a fine-wire point resting on the surface of a relatively high-resistance material, such, for example, as fine porous porcelain which has been. soaked in an electrolyte. In such device, when small voltages are applied, a high re-- sistance appears, nearly all of which resides in the immediate neighborhood of the point. If, however, the voltage across the point is raised, the neighborhood thereof becomes heated and. the resistance of the device falls rapidly.

With such element connected in shunt re lation to the tuned circuit 17 shown in the drawing, it is apparent that, after a definite time lag, as determined by the particular characteristics of. the device 18, the resistance thereof rapidly decreases with increases in the amplitude of the oscillations, hence greatly increasing the effective resistance of the oscillating circuit, by reason of the larger current diverted from the tuned circuit 17 by the resistor 18.

The thermally-responsive resistor element 19 may be one having a large positive tem; perature coeflicient and a definite time lag similar to that of the resistor element 18 in its response to changes in the amplitude of the oscillating currents traversing the platefilament circuit. This element, for example, might comprise a piece of Nolloston wire disposed in a vacuum tube (not shown).

\Vith the resistor element 19 serially disposed in the plate-filament circuit, as indicated in the drawing, it is apparent that, when the oscillations are small, the element is relatively cool and, hence, its resistance is low, but when the amplitude of the oscillations increases, the temperature of the element correspondingly increases and hence its resistance becomes very large.

In order to complete the disclosure of my invention, the operation thereof will be further explained in accordance with theories which appear most plausible in view of my present knowledge of the underlying phenomena, although I do not wish to be limited by such explanation.

\Vhen disturbing impluses, such, for example, as wireless signal impulses, are impressed upon the input circuit of the system the resulting oscillations rapidly increase in amplitude to large values by reason of the large negative damping effect of the system. The oscillations continue to increase in amplitude for a period of time depending upon the time lag of the resistor elements 18 and 19. At the expiration of said time lag, the resistance of the resistors 18 and 19 rapidly varies in opposite directions, as previously described. The oscillations, however, continue to increase in amplitude until the energy losses in the system, as practically determined by the resistors 18 and 19, is greater than the feed back energy, whereupon the oscillations are rapidly damped. When the resistances of the elements 18 and 19 have returned to their initial values, by reason of the cooling of the same, the effect of the disturbing impulses, if still present, is to cause the foregoing cycle to be again repeatedv While two resistor elements are mentioned in the foregoing description, it is apparent that my system is effective when only one is employed.

.It will be observed that the maximum amplitude of the intermittent oscillations is determined by the intensity of the impulses initially unbalancing the system.

lVhen the system embodying my invention is to be employed for the detection of wireless impulses, the constants are so adjusted that the distributing impulses always present are of sufficient intensity to maintain the system oscillating intermittently. Such oscillations produce substantially no effect upon the translating device 15, inasmuch as the initial intensity of the disturbing impulses is extremely small. lVhen signals are impressed upon the system, the amplitude of the intermittent oscillations is increased in accordance with the intensity of the signals. i

The frequency of the intermittent oscillation is determined by the character of the wireless signals to be detected. Thus, for undamped-wave telegraph signals, the in termittent oscillation is caused to occur at an audible frequency, thereby eliminating the necessity for employing the usual heterodyning step. However, when receiving wireless telephone signals, the intermittent oscillation should occur at super-audible frequencies. Other applications of my invention will readily suggest themselves to those skilled in the art.

While I have shown but one embodiment of my invention, for the purpose of describing the same and illustrating its principles and applications, it is capable of various changes and modifications without departing from the spirit thereof and I desire, therefore, that only such limitations shall be imposed thereon as are demanded by the prior art or are specifically set forth in the appended claims.

I claim as my invention 1. In an electrical system, a regenerative feed-back system adapted to generate continuous oscillations upon an unbalancing of the same and thermally-responsive means associated therewith for causing said system to oscillate intermittently.

2. In an electrical system, a regenerative feed-back system adapted to generate con tinuous oscillations upon an unbalancing of the same and thermally-responsive means having a definite time lag associated therewith for causing said system to oscillate intermittently.

3. In an electrical system, a regenerative feed-back system. adapted to generate sustained oscillatory currents upon an unbalancing thereof and thermally-responsive means having a high positive temperature coefticient'and a definite time lag in its response to changes in the amplitude of said oscillatory currents for causing said system to oscillate intermittently.

4C. In an electric system. a regenerative feed-back system adapted to" generate sustained oscillatory currents upon an unbalancing thereof and thermally-responsive means having a high negative temperature coefiicient and a definite time lag in its response to changes in the amplitude of the alternating voltages in said system for causing the feed-back system to oscillate intermittently.

5. In an electrical system, a regenerative system adapted to generate sustained oscillatory currents, an element having a positive temperature coefiicient with a definite time lag and a second element having a negative temperature coefficient, said elements being so associated with said system as to cause the same to oscillate intermittently.

6. In an electrical system, a regenerative feed-back system adapted to generate sustained oscillatorycurrents upon an unbalancing thereof and thermally-responsive means comprising an element having a high positive temperature coefficient and a definite time lag in its response to changes in the amplitude of said. oscillating currents and a second element having a high negative tem perature coefficient and a definite time lag in its response to changes in the alternating potentials in said system, said elements being so associated with said system as to cause the same to oscillate intermittently.

7. In an electrical. system, a regenerative feedback system adapted to generate continuous oscillations upon an unbalancing of the same, means carrying disturbing impulses tending to unbalance said system and thermally-responsive means associated with said feed-back system for causing the same to oscillate intermittently during the presence of said disturbing impulses only.

8. In an electrical system, a regenerative feed-back system adapted to generate continuous oscillations upon an unbalancing of the same, means carrying disturbing impulses tending to unbalance said system and thermally-responsive means associated With said feedback system for causing the same to oscillate intermittently, the amplitude of said intermittent oscillations being modulated in accordance with the varying intensity of said disturbing impulses.

9. In a regenerative feed-back circuit, an evacuated electric device, input and output circuits therefor so associated as to cause said device to function as an oscillator and a thermally-responsive device having a time lag in its response, whereby the positive damping of said system may be periodically,

varied.

10. In a regenerative feed-back circuit, an evacuated electric device, input and output circuits therefor so adjusted as to cause said device to function as a generator of highfrequency oscillations and a thermally-responsive element having a high positive temperature coefficient and a definite time lag in its response to changes in the amplitude of said oscillatory currents included in said output circuit, whereby said system is caused to oscillate intermittently.

11. In a regenerative feed-back circuit, an evacuated electric device, input and output circuits therefor, a feed-back coupling therebetween so adjusted as to cause said system to function as a generator of high-frequency oscillations and a thermally-responsive ele ment having a high negative temperature coefficient and a definite time lag in its response to changes in the amplitude of the alternating voltages in said system included in shunt circuit relation to said coupling, whereby said system is caused to oscillate intermittently.

12. In a regenerative feed-back circuit, an evacuated electric device, input and output circuits therefor so adjusted as to cause said system to function as a generator of highfrequency oscillations and thermally-responsive means comprising an element having a high positive temperature coefficient and a definite time lag in its response to changes in the amplitude of said oscillating currents and a second element having a high negative temperature coefficient and, a definite time lag in its response to changes in the alternating potentials in said system included in said output circuit in such manner that said system is caused to oscillate intermittently.

13. In a wireless receiving system, an antenna circuit, a three-electrode tube, input and output circuits therefor, said antenna circuit and said input circuit being operatively associated, a coupling coil individual to each of said input and output circuits, said coupling coils being so adjusted as to admit of said tube functioning as an oscillator, a seriesconnected element having a high positive temperature coefficient and a definite time lag and a condenser connected in shunt to said inductance coil-in said output circuit and an element having a high negative temperature coefficient and a time lag in shunt relation to said first-mentioned element.

14;. In an electrical system, a regenerative feed-back system adapted to generate sustained oscillatory currents upon an unbalancing thereof and a thermally-responsive resistor element having a high positive temperature coefficient and a definite time lag in its response to changes in the amplitude of said oscillatory currents for causing said system to oscillate intermittently.

15. In an electric system, a regenerative feed-back system adapted to generate sus tained oscillatory currents upon an unbalancing thereof and a thermally-responsive resistor element having a high negative temperature coefficient and a definite time lag in its response to changes in the amplitude of the alternating voltages in said system for causing said system to oscillate intermittently.

16. In a device of the character described, a regenerative feed-back system including an an'iplifying device, input and output am-.,

pliiier circuits therefor, a feed-back coupling therebetween, said coupling being such that the energy supplied thereby is normally greater than the losses in said system, and a variable resistor shunting said coupling.

17. The method of operating a regenera tive feed-back system including an amplifying device, input and output amplifier circuits therefor, a teed-back coupling therebetween, said coupling being such that the energy supplied thereby is normally greater than the losses in said system, and a variable resistor shunting said coupling, said method consisting in causing the resistance of said resistor to be reduced, periodically, to a value such that the energy losses in the systerm are greater than the energy supplied by said feedback coupling.

18. In a device 01'? the character described, a regenerative feed-back system including an ampliiiyingdevice, input and output amplifier circuits therefor, a feed-back coupling therebetween, said coupling being such that the energy supplied thereby is normally greater than the losses in said system, and automatically operating variable-resistance means shunting said coupling for causing said system. to oscillate intermittently.

19. In a device of the character described, a regenerative feed-back system including an. amplifying device, input and output aIn plifier circuits therefor, an anti-resonant circuit including parallel-connected condensive and inductive reactors serially included in one of said amplifier circuits, a feed-back coupling between one of said reactors and the other of said amplifier circuits, sa1d coupling being such that the energy sup plied thereby is normally greater than the losses in said system, and a variable resistor in series-circuit relation to the other of said reactors.

20. In a device of the character described, a regenerative feed-back system including an amplifying device, input and output amplifier circuits therefor, an anti-resonant.

circuit including parallel-connected condensive and lnductlve reactors serially included in one of said amplifier circuits, a feed-back plifier circuits therefor, a feed-back cou-' pling therebetvveen, said coupling'including an anti-resonant circuit and normally supplying greater energy than the losses in the system, and automatically operating means for periodically varying the sharpness of tuning said anti-resonant circuit. I

In testimony whereof, {I have hereunto subscribed my name this 20th day of December JOSEPH SLEPIAN. I 

